Heptene manufacture process



United States Patent Delaware N0 Drawing. Filed Apr. 30, 1965, Ser. No. 452,334

Claims. (Cl. 260-68315) This is a continuation-in-part of copending and now abandoned application Serial No. 164,389 filed January 4, 1962 which in turn was a continuation-in-part of Serial No. 781,423, filed December 19, l958 and now abandoned.

This invention relates, in general, to an improved process for the manufacture of heptenes by copolymerization of C olefins with C olefins and, more particularly, relates to the use of'isobutylene dimer available as a by-product from various refinery processes in addition to or in place of at least part of the C olefins conventional used in this copolymerization process. In apreferred embodiment, the present invention relates to an optimum process for copolymerizing propylene with a. substantial amount of isobutylene dimer and with a refinery C unsaturate stream, for example, from catalytic cracking, to obtain heptenes.

The instant invention is especially advantageous inasmuch as isobutylene dimer is available in relatively large amounts as a by-product from various refinery processes. For example, in separating the various butylenes from streams containing a mixture thereof, it is customary to efiect the removal of isobutylene either by simple sulfuric acid extraction or by sulfuric acid-catalyzed dimerization to diisobutylene, followed by distillation. Even in the former case, considerable quantities of diisobutylene are unavoidably formed. conventionally, the dimer is disposed of by adding it to gasoline as a blending stock. Obviously, its dollar value as a gasoline component is not great and would be markedly enhanced were the dimer employed in the production of chemicals. The process of the present invention provides such a use for the production of chemicals.

It has now been found that the addition of a substantial amount of diisobutylene to the C -C unsaturate feed stream utilized for conventional heptene polymerization processes surprisingly increases the yield of heptene. That is to say, whenheptene is produced by passing propyleneand butylene-containing feeds over conventional polymerization catalysts, the addition of a substantial amount of diisobutylene to said streams in addition to or in place of at least part of the C olefins enhances the yield of heptene, while providing numerous other advantages. Thus, in accordance with the present invention, when isobutylene streams are to be used in the production of C olefins, it is unnecessary to remove diisobutylene therefrom prior to such use. Additionally, any C material either unreacted or formed during the copolymerization process can be recovered and used for gasoline blending. Hence, the present process provides a manner of utilizing diisobutylene which, economically, is attractive, inasmuch as that diisobutylene which is not upgraded by conversion to heptenes is not lost, but instead, serves a useful purpose.

It should also be noted that a dimer stream may be used which contains small amounts of trimer or higher polymers which usually are found in commercial dimer streams. In addition, prior to feeding the dimer stream to the polymerization zone, it is preferred to remove the usual trace amounts of sulfuric acid esters present by conventional treatment such as redistillation, hot caustic treating, bauxite treating, etc.

The heptenes formed in the copolymerization process of the invention find utility commercially, for example, in the manufacture of isooctyl alcohol by the 0x0 process.

Since the present process is involved principally with the substitution of or addition to the feedstock in an otherwise conventional polymerization process whereby epterre is formed from C and C olefins, the process steps will be only generally and briefly described. Thus, polym erization is carried out with any of the known catalysts under conditions to obtain high yields of the desired 0;

material.

The propene-butene'charging stock utilized with the isobutylene dimer may be of a wide variety of compositions, but preferably contains very little water. Both olefins and parafi'ins may be charged to the process in the C and C feed streams, although it is preferred that specifically isobutylene be used as the Cl, olefin to obtain maximum C yields.

Some of the catalysts which may be used for the present polymerization are copper pyrophosphate and liquid phosphoric acid of to weight percent strength, used either in bulk or as a film on quartz chips. This phosphoric acid catalyst may also be used on kieselguhr, diatomaceous earth or silica, on which it is precalcined at about 400 to 500 F. The catalyst tends to lose activity by undergoing complete dehydration; therefore, a small amount of Water or steam is added to the charging stock, e.g. to maintain the activity, The polymerization reaction is conducted under a pressure of 250 to 3000 p.s.i.g., preferably 500 to 1500, e.g. 1000 p.s.i.g., at temperatures of 280 to 550 F. preferably 350 to 450, e.g. 400 F. Since the polymerization reaction is exothermic, heat is removed if necessary from the reaction zone to maintain these desired temperatures. Other polymerization catalysts may be used, with temperature and pressure conditions appropriate for the particular catalyst. For example, with a catalyst such as BF lower temperatures and pressures than described above would be employed.

In accordance with the present invention, the proportion of dimer which is added to the C olefin feed or to the C +C olefin feed can vary within wide limits. Thus, even small amounts of dimer will increase the yield of C olefin'product to some extent. Consequently, the extreme lower limit on the amount of said dimer to be added depends upon practical, rather than theoretical considerations. Hence, the lower limit of dimer which is added to the reaction stream can broadly be stated as that amount which produces a sufiicient increase in C product to make such addition economically feasible. The present invention, therefore, contemplates the addition of dimer in amounts substantial enough to effect significant increase in the yield of C olefin product. For the purposes of this invention, the amount of diisobutylene added to the olefin feed stream is always to be calculated as equivalent isobutylene.

As to the maximum amount, obviously some point is reached where the relative proportion of propylene becomes so low that the desired polymerization reaction is hindered. In its broad aspects, therefore, the invention contemplates the addition to the C or C +C feed streams of an amount of diisobutylene substantial enough to significantly increase the yield of C olefin product and not hinder the preparation of same.

Specifically, sufficient dimer to etfect the desired results of the present invention constitutes amounts such as to provide a mole ratio of combined C olefins and dimer (dimer being calculated as equivalent isobutylene) to C of from about 0.15 to 3/1, preferably 0.3 to 3/1. Maximum yields of C olefin product are attained when the mole ratio of C to combined C olefin and dimer is approximately 1.

It is to be understood, however, that the amount of dimer addition contemplated so as to effect especially advantageous yields in C product is at least about 0.15 mole of dimer per mole of C feed (see Table III hereinafter). Likewise, the invention contemplates use of no more than 3.0 moles of dimer per mole of C feed. In view of the foregoing, it may be postulated that when a feed comprised essentially of C olefin is utilized, the mole ratio of diisobutylene to C olefin feed is Within the range of about 0.15 to 3/1 (see Table I hereinafter), preferably 0.3 to 3/ 1.

It has also been found that dimer addition is somewhat more perfected when the C olefin which is utilized'with the C olefin is substantially n-butene than when the C olefin is mainly isobutylene.

When the catalyst is commercial kieselguhr-supported phosphoric acid (so-called solid phosphoric acid catalyst),

feed rates used are in the range of 0.01 to 2.0 gallons of total feed per hour per pound of catalyst, preferably 0.05

to 0.50, e.g. 0.20 gallon per hour per pound of catalyst. Such feed rates exclude any coolant which may be injected throughout the reactor. Part or all of the dimer stream might also be used as the coolant. The monomer olefin content of the feed is generally 10 to 70 mole percent, preferably 20 to 50 mole percent, e.g. 40 mole percent. Propane .and/ or butanes, preferably butanes, may be recycled to dilute the fresh feed olefin to the desired olefin content to help maintain suitable reactor temperature control. Since dimer appears to undergo depolymerization to the monomer prior to reaction with propylene to produce C and since such depolymerization absorbs heat, dimer addition may serve to reduce the requirement for parafiin recycle.

It is also contemplated in the present process that material in the efiluent from the polymerization zone higher boiling than the C material may be recycled to the process to increase the yield of C material obtained.

The following data are presented to illustrate the excellent quality of diisobutylene as a feedstock in place of the conventional C materials used in the prior art copo-.

lymerization to C olefins processes. In Table I data are presented on C yields Where only dimer is added to propylene, and Table II presents data where also n-butene is used in addition to the dimer with the propylene.

TABLE I.EFFEGT OF DIMER ADDITION WITH PROPYLENE FEED Total Polymer Produced, Wt. percent on Propylene Fe Propylene Conversion, percent Ratio, C3 in Product/C3 Fed 0. 42 0.58 Total Polymer Composition? Wt. percent C 39.0 31.0 4. 4 4. 0 Wt. percent Cs 24. 2 33. 3 6.0 58.1

a Pure dimer l'cd, without propylene. b Wt. percent on dimer fed. 0 Analysis by low-voltage mass spectrometer.

TABLE II.EFFECT OF DIMER ADDITION \VITH PROPYLENE-u-BUTYLENE FEED Run E F G 11 Temperature, F 400 400 446 446 Pressure, p.s.i.g 800 800 l, 000 1,000

Total Feed s itividity,"ZiijiiEf ilii O yst atal 0.18 0.21 0.30 0.32 Monomer Feed Composition, Wt. Percent:

Monomer Feed Comp Mol Pc Total Butylenes on [otalOlefins Dimer Addition Rate, Wt. Percent mer Olefin Fed Total Polymer Produced, Wt. Percen Monomer Olefins Fed 81 123 86 92 Olefin Conversion, Wt. Percent:

Propylene Total Monomer Olefins Ratio, C5 in Product/Cs Fed Total Polymer Composition:

Wt. Percent C 30.

Wt. Percent C5 14.

From this data it can be. clearly seen that high yields of the C material are obtained when using isobutylene dimer rather than the monomer as in the present process. It is considered that these results are unexpected since it would be supposed that the isobutylene dimer would polymerize with the olefins present to form higher boiling materials.

The excellent quality of the isobutylene dimer in place of the monomer as a feed can be seen from calculations based on Tables I and II which are given below in Table III.

TABLE III.-DIMER ADDITION AS EQUIVALENT TO, OR BETTER THAN ISOBUIYLENE ADDITION Run E F Feed Composition (100% Olefin Basis):

Mol Percent Propylene 74. 4 (l9. 7 M01 Percent n-Butylene 12.0 14.8 Mol Percent Dimer (calculated as eqtnvaleut isobutylene) 13. o 15. 5

Total 100. 0 100.0

0 Yield Wt. Percent on Total Polymer:

1 Actual 30. 2 29. 0

Predicted (based on an equivalent amount of monomer being used instead of the dimer 2 23-24 25-28 1 Predicted by extrapolation and interpolation of C7 yield data of Runs 0, G and H.

2 Actual run advantage may not be quite so large because actual Run E had rather low conversion (67%) which is known to enhance C; yield by limiting further polymerization of C7 to C10 and C11, etc.

What is claimed is:

1. In a process for preparing a C olefin from a C to C hydrocarbon stream containing at least 20 mole percent olefin and consisting essentially of propylene and nbutylenes wherein said stream is contacted with a phosphoric acid catalyst at the rate of about 0.05 to 0.5 gallons per hour per pound of catalyst in a polymerization zone at temperatures of 280 to 550 F. and pressures of 250 to 3000 p.s.i.g. to produce said O; olefin, the improvement which consists of adding to said stream between about 0.15 to 3 moles of diisobutylene (calculated as equivalent isobutylene) per mole of propylene, thereby substantially increasing the yield of said C olefin.

2. The process of claim 1 in which 0.3 to 3 moles of diisobutylene (calculated as equivalent isobutylene) per mole of propylene is added to said hydrocarbon stream.

3. The process of claim 1 in which the temperature is about 350 to 450 F.

4. The process of claim 1 in which the catalyst is phosphoric acid calcined on kieselguhr.

5. In a process for preparing a C, olefin from a C hydrocarbon stream containing at least 20 mole percent olefin and consisting essentially of propylene, wherein said stream is contacted with a phosphoric acid catalyst at the rate of about 0.05 to 0.5 gallons per hour per pound of catalyst in a polymerization zone at temperatures of 280 to 550 F. and pressures of 250 to 3000 p.s.i.g. to produce said C olefin, the improvement which consists of adding to said stream between about 0.15 to 3 moles of diisobutylene (calculated as equivalent isobutylene) per mole of propylene, thereby substantially increasing the yield of said (3-; olefin.

References Cited by the Examiner UNITED STATES PATENTS 2,116,157 5/1938 Morrell 260-683.l5 2,182,617 12/1939 Michel 260-68315 6' 2,658,933 11/1953 May et al 260-683.15 2,694,002 11/1954 Hays, 260-683.15 2,695,326 11/1954 Lippincott et a1. 260683.15

5 OTHER REFERENCES Ipatieif et al., Industrial & Engineering Chemistry, vol. '37 (1945), pages 362-364.

10 PAUL M. COUGHLAN, Primary Examiner. 

1. IN A PROCESS FOR PREPARING A C7 OLEFIN FROM A C3 TO C4 HYDROCARBON STREAM CONTAINING AT LEAST 20 MOLE PERCENT OLEFIN AND CONSISTING ESSENTIALLY OF PROPYLENE AND NBUTYLENES WHEREIN SAID STREAM IS CONTACTED WITH A PHOSPHORIC ACID CATALYST AT THE RATE OF ABOUT 0.05 TO 0.5 GALLONS PER HOUR PER POUND OF CATALYST IN A POLYMERIZATION ZONE AT TEMPERATURES OF 280* TO 550*F. AND PRESSURES OF 250 TO 3000 P.S.I.G. TO PRODUCE SAID C7 LEFIN, THE IMPROVEMENT WHICH COMSISTS OF ADDING TO SAID STREAM BETWEEN ABOUT 0.15 TO 3 MOLES OF DIISOBUTYLENE (CALCULATED AS EQUIVALENT ISOBUTYLENE) PER MOLE OF PROPYLENE, THEREBY SUBSTANTIALLY INCREASING THE YIELD OF SAID C7 OLEFIN. 